Thank you for using our online answers forum. I am sorry to hear you are having audio issues with your new Slingbox 500. Do you also have component cables setup on the Slingbox? If you do also have the component setup are you getting audio out of that input? Have you tried using an alternate HDMI cable?
Here are a few links to help you to try and troubleshoot the issues.
Hope these help, feel free to reply back with any other question's or concerns you have.
The Sling Moderation Team